Re: [PATCH] Staircase scheduler v7.4
From: Nick Piggin
Date: Mon Jun 28 2004 - 23:46:08 EST
Peter Williams wrote:
Nick Piggin wrote:
Felipe Alfaro Solana wrote:
I have tested 2.6.7-bk10 plus from_2.6.7_to_staircase_7.7 patch and,
while it's definitively better than previous versions, it still feels a
little jerky when moving windows in X11 wrt to -mm3. Renicing makes it a
little bit smoother, but not as much as -mm3 without renicing.
You know, if renicing X makes it smoother, then that is a good thing
IMO. X needs large amounts of CPU and low latency in order to get
good interactivity, which is something the scheduler shouldn't give
to a process unless it is told to.
I agree. Although the X servers CPU usage is usually relatively low
(less than 5%) it does have periods when it can get quite high (greater
than 80%) for reasonably long periods. This makes it difficult to come
up with a set of rules for CPU allocation that makes sure the X server
gets what it needs (when it needs it) without running the risk of giving
other tasks with similar load patterns unnecessary and unintentional
preferential treatment.
Well exactly. This is what the standard scheduler tries to do, and
it does have weird starvation and priority problems that pop up.
However, I think that there is still a need for automatic boosts for
some tasks. For instance, programs such as xmms and other media
streamers are ones whose performance could worsen as a result of the X
server being reniced unless it is treated specially and the boost they
are given needs to be enough to put them before the X server in priority
order. But renicing X would enable a tightening of the rules that
govern the automatic dispensing of preferential treatment to tasks that
are perceived to be interactive which should be good for overall system
performance.
I agree renicing X is helpful.
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